The initial goal is to determine if viral activation occurs following blood transfusion and if leukocyte depletion or irradiation can prevent it. Both clinical and laboratory data will be collected. Both CMV and HIV-1 will be studied in HIV-1 infected transfusion recipients. The initial part of the study will enroll 330 HIV-1 infected patients at the time they are scheduled for transfusion. The effects of gamma irradiation and leukocyte reduction on CMV and HIV viremia will be examined using quantitative PCR and viral culture. The effect of repeated transfusion, if needed, will also be assessed. Clinical data will be collected on transfused patients. The study will be a multicenter study of 330 HIV-1 infected patients with CD4 counts below 250 cell/cc3. Patients scheduled for transfusion will be entered into the study at the time of their first transfusion and randomized to one of three arms: to receive unmanipulated blood components, filtered blood, or irradiated blood. Patients will receive blood components treated in this way for a period of one to two years. Blood samples will be taken from the individuals before transfusion and at varying intervals after transfusion. These samples will be studied using the polymerase chain reaction technology and quantitative culture to determine if activation of CMV or HIV-1 occurs following transfusion. These tests will also be done at intervals when the patient is not being transfused to determine the values at baseline. These individuals will also be tested for a number of other immunological markers as determined by the steering committee. The individuals will also be examined by a physician regularly and monitored for the presence of opportunistic infection.